1. Field of the Invention
The present invention relates to an image sensor, and more particularly, to an image sensor which is capable of increasing sensitivity and reducing crosstalk.
2. Description of the Prior Art
Please refer to FIG. 1. FIG. 1 shows a sectional diagram of a conventional image sensor 100. As shown in FIG. 1, The image sensor 100 comprises: a substrate 110, three photodiodes 112, 114, 116, a first insulation layer 120, an anti-reflective coating (ARC) layer 130, a second insulation layer 140, and a color filter array 150. The photodiodes 112, 114, 116 are disposed in the substrate 110. The first insulation layer 120 is disposed on the substrate 110 and the photodiodes 112, 114, 116. The ARC layer 130 is disposed on the first insulation layer 110. The second insulation layer 140 is disposed on the ARC layer 130. The color filter array 150 is disposed on the second insulation layer 140, and the color filter array 150 comprises color filters, such as a red monochromatic color filter 152, a green monochromatic color filter 154, and a blue monochromatic color filter 156. Reflection is more severe when light goes from the second insulation layer 140 to the first insulation layer 120 when the change in refractive index of the first insulation layer 120 and the second insulation layer 140 is large. Thus, the ARC layer 130 is utilized to reduce reflection. However, the ARC layer 130 with a uniform thickness is not optimized for different colors of light.